Routing Instances Overview

You can create multiple instances of BGP, IS-IS, LDP, Multicast Source Discovery Protocol (MSDP), OSPF version 2 (usually referred to simply as OSPF), OSPF version 3 (OSPFv3), Protocol Independent Multicast (PIM), RIP, and static routes by including statements at the following hierarchy levels:

Note: You can also create multiple routing instances for separating routing tables, routing policies, and interfaces for individual DHCP wholesale subscribers (retailers) in a layer 3 wholesale network. For information about how to configure layer 3 wholesale network services, see the Junos Broadband Subscriber Management Solutions Guide.

A routing instance is a collection of routing tables, interfaces, and routing protocol parameters. The set of interfaces belongs to the routing tables, and the routing protocol parameters control the information in the routing tables.

You can configure eight types of routing instances: forwarding, Layer 2 control (MX Series routers only), Layer 2 virtual private network (VPN), nonforwarding, VPN routing and forwarding (VRF), virtual router, virtual private LAN service (VPLS), and virtual switch (MX Series routers only).

Each routing instance has a unique name and a corresponding IP unicast table. For example, if you configure a routing instance with the name my-instance, the corresponding IP unicast table is my-instance.inet.0. All routes for my-instance are installed into my-instance.inet.0.

Note: The default routing instance, master, refers to the main inet.0 routing table. The master routing instance is reserved and cannot be specified as a routing instance.

Each routing instance consists of sets of the following:

You can configure eight types of routing instances:

Configure global routing options and protocols for the master instance by including statements at the [edit protocols] and [edit routing-options] hierarchy levels. Routes are installed into the master routing instance inet.0 by default, unless a routing instance is specified.

Multiple instances of BGP, OSPF, and RIP are used for Layer 3 VPN implementation. The multiple instances of BGP, OSPF, and RIP keep routing information for different VPNs separate. The VRF instance advertises routes from the customer edge (CE) router to the provider edge (PE) router and advertises routes from the PE router to the CE router. Each VPN receives only routing information belonging to that VPN.

Forwarding instances are used to implement filter-based forwarding for Common Access Layer applications.

PIM instances are used to implement multicast over VPN applications.

Nonforwarding instances of IS-IS and OSPF can be used to separate a very large network into smaller administrative entities. Instead of configuring a large number of filters, nonforwarding instances can be used to filter routes, thereby instantiating policy. Nonforwarding instances can be used to reduce the amount of routing information advertised throughout all components of a network. Routing information associated with a particular instance can be announced where required, instead of being advertised to the whole network.

Layer 2 VPN instances are used for Layer 2 VPN implementation.

Virtual router instances are similar to a VPN routing and forwarding instance type, but used for non-VPN-related applications. There are no VRF import, VRF export, VRF target, or route distinguisher requirements for this instance type.

Use the VPLS routing instance type for point-to-multipoint LAN implementations between a set of sites in a VPN.

For more detailed information about configuring VPNs and Layer 2 VPNs, see the Junos VPNs Configuration Guide.

For more detailed information about configuring virtual switches and Layer 2 services on MX Series routers, see the Junos Layer 2 Configuration Guide and the Junos MX Series Ethernet Services Routers Solutions Guide.

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